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Commit b5db0e38 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Revert "x86 PAT: remove CPA WARN_ON for zero pte" 



This reverts commit 58dab916, which
makes my Nehalem come to a nasty crawling almost-halt.  It looks like it
turns off caching of regular kernel RAM, with the understandable
slowdown of a few orders of magnitude as a result.

Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 647df518

arch/x86/mm/pageattr.c

+4 −6
Original line number Diff line number Diff line
@@ -555,12 +555,10 @@ static int __change_page_attr(struct cpa_data *cpa, int primary) 
	if (!pte_val(old_pte)) {

		if (!primary)

			return 0;



		/*

		 *  Special error value returned, indicating that the mapping

		 * did not exist at this address.

		 */

		return -EFAULT;

		WARN(1, KERN_WARNING "CPA: called for zero pte. "

		       "vaddr = %lx cpa->vaddr = %lx\n", address,

		       *cpa->vaddr);

		return -EINVAL;

	}



	if (level == PG_LEVEL_4K) {

arch/x86/mm/pat.c

+13 −32
Original line number Diff line number Diff line
@@ -505,35 +505,6 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size) 
}

#endif /* CONFIG_STRICT_DEVMEM */



/*

 * Change the memory type for the physial address range in kernel identity

 * mapping space if that range is a part of identity map.

 */

static int kernel_map_sync_memtype(u64 base, unsigned long size,

					unsigned long flags)

{

	unsigned long id_sz;

	int ret;



	if (!pat_enabled || base >= __pa(high_memory))

		return 0;



	id_sz = (__pa(high_memory) < base + size) ?

						__pa(high_memory) - base :

						size;



	ret = ioremap_change_attr((unsigned long)__va(base), id_sz, flags);

	/*

	 * -EFAULT return means that the addr was not valid and did not have

	 * any identity mapping. That case is a success for

	 * kernel_map_sync_memtype.

	 */

	if (ret == -EFAULT)

		ret = 0;



	return ret;

}



int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,

				unsigned long size, pgprot_t *vma_prot)

{
@@ -584,7 +555,9 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, 
	if (retval < 0)

		return 0;



	if (kernel_map_sync_memtype(offset, size, flags)) {

	if (((pfn < max_low_pfn_mapped) ||

	     (pfn >= (1UL<<(32 - PAGE_SHIFT)) && pfn < max_pfn_mapped)) &&

	    ioremap_change_attr((unsigned long)__va(offset), size, flags) < 0) {

		free_memtype(offset, offset + size);

		printk(KERN_INFO

		"%s:%d /dev/mem ioremap_change_attr failed %s for %Lx-%Lx\n",
@@ -632,7 +605,7 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot, 
				int strict_prot)

{

	int is_ram = 0;

	int ret;

	int id_sz, ret;

	unsigned long flags;

	unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
@@ -673,7 +646,15 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot, 
				     flags);

	}



	if (kernel_map_sync_memtype(paddr, size, flags)) {

	/* Need to keep identity mapping in sync */

	if (paddr >= __pa(high_memory))

		return 0;



	id_sz = (__pa(high_memory) < paddr + size) ?

				__pa(high_memory) - paddr :

				size;



	if (ioremap_change_attr((unsigned long)__va(paddr), id_sz, flags) < 0) {

		free_memtype(paddr, paddr + size);

		printk(KERN_ERR

			"%s:%d reserve_pfn_range ioremap_change_attr failed %s "